THE,. EYE OP PECTEN. 



101 



(siplional) of Cardium. In both cases there are two series o£ 

 recipient cells and the retinas are inverted. 



There are some interesting analogies; thus, for example, 

 the ocelli of Agrion (a dragon fly) possess a retina which has 

 also two series of recipient cells very like the rod-cells with 

 rods and the distal cells of Pecten, but there is no inversion. 



Text-fig. 2. 



O^.y efitK N<.YVt,)>roi,i"aHvcLrrk Ob.i, J)isW Orwdv o| tKhc He/i^t 



We are also familiar in the vertebrate eye with two kinds of 

 recipient structures — the rods and cones — though these bodies 

 are situated in practically the same layer (Bernard [36] has, 

 however, stated that in Amphibia the cones are earlier stages 

 in the development of new rods). 



When all things are taken into consideration the eye [of 

 Pecten and also of Spondylus appears a very remarkable 



